Multiple filament incandescent lamp



May 18, 1948. L. M. HERTZ 2,441,815

MULTIPLE FILAMENT INCANDESCENT LAMP Filed May 2, 1947 lnvervtor: Les tev M. Her'bz,

His Attorney.

Patented May 18, 1948 MULTIPLE FILAMENT INCANDESCENT LAMP Lester M. Hertz, Cleveland, Ohio, mignor to General Electric Company, a corporation of New York Application May 2, 1947, Serial No. 745,496

My invention relates to electric incandescent lamps in general and, more particularly, to a multiple filament signaling lamp adapted to emit beams of difierent colors upon independent energization of the filaments.

Light signaling means are in use at present on airplanes for flashing two alternate light beams or position signals of different colors, usually red and white. At present, two separate lamps are employed for this purpose, the two lamps being mounted in a housing provided with a suitable color filter and being alternately energized to produce the two differently colored light beams.

It is an object of my invention to provide a multiple filament electric incandescent lamp of novel design which will emit differently coloredlight beams forwardly of the lamp when its filaments are independently energized.

Another object of my invention is to provide an electric incandescent lamp of the above-mentioned character suitable for use as a signalin lamp on airplanes, which lamp will withstand the shocks and vibrations attending such use.

Further objects and advantages of my invention will appear from the following description of species thereof and from the accompanying drawing-in which:

Fig. 1 is an elevation, partly in section, of an electric incandescent lamp comprising my invention; Fig. 2 is a transverse section on the line 2-2 of Fig. 1; Fig. 3 is a fragmentary perspective view, partly broken away, of the mount structure shown in Fig. 1; Fig. 4 is a view similar to Fig. 1 showing a modified form of mount structure according to the invention; Fig. 5 is a transverse section on the line 5-5 of Fig. 4; and Fig. 6 is a fragmentary view of another modified form of mount structure according to the invention.

Referring to the drawings, the lamp there shown comprises a short tubular bulb or envelope l of clear glass provided at its neck end with a re-entrantstem 3 forming a, part of the mount I 2 of the lamp. The stem 3 extends into the bulb l in the direction of its axis and is provided with a press portion 4 within which a plurality (three in this case) of lead-in wires or in-leads 5, 6, 'l are sealed. The said lead-in wires are connected at their outer ends to separate terminals on a bayonet type base 8 mounted on the bulb, so as to provide two separate electrical supply circuits. Lead-in wire 5 is connected to the shell 9 of the base 8 and serves as a common lead for the two electrical supply circuits. The two other leads 6 and I are connected, respectively, to bottom contacts or eyelets i 0 and I l on the base.

' The lead-in wires or in-leads 5, 6 and l extend into the bulb from the stem press 4 in the general direction of the bulb axis and arranged in triangular relation, with the in-leads 5, l disposed 'inalplane including the bulb axis and the in-lead 8 disposed substantially mid-way between the in-leads 5, 'l but offset to one side of the plane thereof. At corresponding points intermediate the stem press I and their inner ends, the lead-in wires 5, 1 are bentlaterally outward and away from each other to form laterally extending 011'- set portions I2, It to which are connected the ends of an incandescible filament i4, preferably in the form of a coiled tungsten wire. A second filament i 5, similar to the filament I4, is connected across the inner ends of the lead-in wires 5 and 8. As shown, the two filaments I 4, I! are spaced laterally of .the bulb axis, with the lower 1 filament l4 more or less centered with respect to the bulb axis and lying in the plane of the lead-in wires 5, 1 and with the upper filament I 5 offset slightly to one side of the bulb axis (Fig. 2).

Mounted on the lead-in wires 5, 8, 1 between the two filaments l4, I5 is a cupped or concave color filter or shield I 6, preferably of colored glass. for transmitting light rays within a certain color band only of the light spectrum. For the particular airplane signaling purpose for which the illustrated lamp is intended to be used, a red filter It is employed for transmitting only those radiations in the red color band or near thereto. The color filter I6 is mounted on the lead-in wires in a position centered wth respect to the bulb axis, with its concave or recessed side facing the stem 3 and at least partially enclosing the lower-most filament l4 so as to intercept the cone of light rays emanating from the said filament within a cone angle of approximately 180 or thereabouts.

For supporting the filter IS in place on the leadin wires, apertures I! are provided in the filter through which the lead-in wires extend with a close fit therebetween. The lead-in wires 5, 8, 1 thus hold the filter It in place laterally of the bulb. For holding the fi-lter I 6 in place longitudinally of the bulb, suitable retaining means may be provided on the lead-in wires. In accordance with the invention, the said retaining means may comprise slip-over retainer members in the form of wire slip-over coils l8 mounted on the lead-in wires 5, 6, 1 on each side of the filter, with the proximate ends of the pair of slip-over coils on each lead-in wire engaging and compressed against the opposite sides of the filter. The slipover coils l8 are suitably fastened to the lead-in wires (as by welding, for instance) at their ends remote from the filter l6, 1. e., at the distal ends of each pair of slip-over coils on each lead-in wire. whereby the ends of the coil bearing against the filter are free to move along the lead-in wire. Being secured to the lead-in wires under compression, the slip-over coils l8 thus exert a constant spring pressure against the opposite sides of the filter which, coupled with the three-point support of the filter, serves to eiiectively'hold the latter in place on the lead-in wire against tilting or other movement tbereonunder all normal condi-- tions of service of the lamp.

The modified lamp construction shown in Figs. 4 and is similar to that of Figs. 1-3 except that the three lead-in wires I8, and 2| are spread or flared out, inwardly of the stem 3; so as to support the color filter 22 at points more widely spaced than in the case of the form of invention shown in Fig. 1. In this way, a firmer three-point support for the filter is provided. The filter 22 in Figs. 4 and 5 also differs from the filter i8 01 Fig. 1 in that it is provided with a cylindrical extension 23 at its periphery which extends down beyond the lower filament IQ for the purpose of intercepting a great proportion of the light rays from the said filament than in the case of Fig. 1.

Instead of using wire slip-over coils l8 for holding the color filter IE or 22 in place on the lead-in wires, eyelets orhollow rivets 24 may be employed as retaining members for the filter, as shown in Fig. 6. As in the case of the wire coils 18, the eyelets or rivets 24 may be welded in' place on the lead-in wires, with the color filter IE or 22 clamped between the flanged por-' tions 25 of the eyelets.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric incandescent lamp comprising a light-transmitting glass bulb, a plurality of leadin wires sealed through said bulb and extending thereinto, a pair of filaments in said bulb connected across different ones of said lead-in wires for independent energization, a shield disposed ing provided with three triangularly arranged within said bulb between said filaments and provided with apertures through which the lead-in wires extend with a close interfit, and slip-over retainer members fastened on said lead-in wires on opposite sides of said shield and in engagement therewith to hold it in place on said lead-in wires.

2. An electric incandescent lamp comprising a light-transmitting glass bulb, a plurality of leadln wires sealed through said bulb and extending thereinto, a pair of filaments in said bulb connected across diflerent ones of said lead-in wires for independent energization, a shield disposed within said bulb between said filaments and provided with apertures through which the lead-in wires extend with a close interfit, and wire slipover coils fastened on said lead-in wires on opposite sides of said shield and compressed against the said opposite sides of the shield to thereby hold it in place on said lead-in wires.

3. An electric incandescent lamp comprising a light-transmitting glass bulb, three lead-in wires sealed through said bulb and extending thereinto in the general direction of the bulb axis, a Pair of filaments in said bulb spaced longitudinally of the bulb axis and connected across different ones of said lead-in wires for independent energization, a shield disposed transversely within said bulb between said filaments, said shield being provided with three triangularly arranged apertures through which the lead-in wires extend with a close interfit to provide a, three-point support for said shield, and retaining means oneach of said lead-in wires on opposite sides of said shield and in engagement therewith to hold it in place on said lead-in wires.

4. An electric incandescent lamp comprising a light-transmitting glass bulb, three lead-in wires sealed through said bulb and extending thereinto in the general direction of the bulb axis, a

apertures through which the lead-in wires extend with a close interfit to provide a three-point support for saidshield, and a pair or wire slipover coils fastened on each of said lead-in wires on opposite sides of said shield and compressed against said shield to thereby hold it in place on said lead-in wires.

5. An electric incandescent lamp comprising a light-transmitting glass bulb having a re-entrant stem, a plurality of lead-in wires sealed through said stem and extending into the bulb in the general direction of the bulb axis, a pair of filaments in said bulb spaced longitudinally oi the bulb axis and connected across different ones or said lead-in wires for independent energization, a cupped color filter disposed within said bulb between said filaments with its cupped side facing the stem and at least partly enclosing the filament nearest the stem, said filter being provided with apertures through which the lead-in wires extend with a close interfit, and wire slip-over coils fastened on said lead-in wires on opposite sides of said filter and compressed against the said opposite sides 01 the filter to thereby hold it in place on said lead-in wires.

6. An electric incandescent lamp comprising a light-transmitting glass bulb, a plurality of leadin wires sealed through said bulb and extending thereinto, a pair of filaments in said bulb connected across diflerent ones of said lead-in wires for independent energization, a shield disposed within said bulb between said filaments and proagainst the said shield to thereby hold it in place on said lead-in wires.

'7. An electric incandescent lamp comprising a light-transmitting glass bulb, a. plurality of leadin wires sealed through said bulb and extending thereinto, a pair of spaced filaments in said bulb connected across different ones of said lead-in wires for independent energization, a cupped colored glass filter disposed within said bulb between saiid filaments, said filter being provided with a plurality of widely spaced apertures located adjacent the maximum diameter of said filter and said lead-in wires being spaced apart inwardly of the. bulb to extend through the said apertures with a close interfit, and wire slip-over coils fastened on said lead-in wires on opposite sides 01' said filter and compressed against the said opposite sides of the filter to thereby hold it in-place on said lead-in wires.

LESTER M. HERTZ.

REFERENCES CITED The following references are -of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,391,922 Roper Jan. 1, 19 46 

